I've purchased a license about a year ago and successfully used Lightroom until now. Recently I've bought a new notebook, installed Lightroom on it have tried to license it. It said that my serial number is invalid.I login to LWS and can see this serial number under Retrieve Serial Numbers. How can I fix this?

Did you install Lr on your new notebook using a disk or an already downloaded copy, or did you use a download direct from Adobe - if you did the latter, then you probably (if you're not aware of the difference) downloaded the CC version, which does not open with a standalone licence serial number. Is this the case? If it is, you have to uninstall Lr , and then download from here